With the advancement of technology, computers are introduced into recently sold transportation by many manufacturers one after another. In the case of automobiles, the conventional automobiles are not provided with complicated electronic devices, and mostly implemented by mechanical structure only. The currently sold automobiles, however, generally comprise trip computers, and equipment for vehicle state detection and so on, in such a way that electric power management is extremely essential for the current automobiles.
Furthermore, excessive electronic devices are used in the current automobiles, such that it is impossible to supply electric power only by electric generators of the automobiles, instead operating power required for each electronic device must be supplied by a power supply connected to the electric generator. The current power supply, however, mainly comprises an operating power supply unit and a standby power supply unit, in which electric power is generated by the operating power supply unit only when the power supply is started up, while electric power is supplied to the electronic devices, to which the standby power supply unit is connected, by the standby power supply unit incessantly when the power supply is situated in a standby condition. Furthermore, although the current transportation is generally provided with an electric generator and an electricity storage element, electric power is generated by the electric generator only when the transportation is started up, and electric power is also received by and then stored in the electricity storage element only when electric power is generated by the electric generator. Moreover, electricity stored in the electricity storage element is limited, and is reduced day by day until depletion if electric power is acquired by the standby power supply unit from the electricity storage element instead once the transportation is laid off. Then, there is no electric power to start up the transportation the next time inconveniently.